package com.lhx.linked;

public class ReverseList {
    static class ListNode {
        int val;
        ListNode next;
        ListNode(int val) { this.val = val; }
        ListNode(int val, ListNode next) {
            this.val = val;
            this.next = next;
        }
    }

    public static ListNode iterate(ListNode head) {
        ListNode prev = null,next;
        ListNode curr = head;
        while(curr != null) {
            next = curr.next;
            curr.next = prev;
            prev = curr;
            curr = next;
        }
        return prev;
    }

    public static void main(String[] args) {
      ListNode node5 = new ListNode(5,null);
      ListNode node4 = new ListNode(4,node5);
      ListNode node3 = new ListNode(3,node4);
      ListNode node2 = new ListNode(2,node3);
      ListNode head = new ListNode(1,node2);

      ListNode prev =  iterate(head);

        ListNode pre = prev;
      while(pre != null) {
          System.out.println(pre.val);
          pre = pre.next;
      }
        System.out.println(pre);
    }
}

